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src/hotspot/share/gc/shenandoah/heuristics/shenandoahCompactHeuristics.cpp

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41   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahAllocationThreshold,  10);
42   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahImmediateThreshold,   100);
43   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahUncommitDelay,        1000);
44   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahGuaranteedGCInterval, 30000);
45   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahGarbageThreshold,     10);
46 }
47 
48 bool ShenandoahCompactHeuristics::should_start_gc() {
49   size_t max_capacity = _space_info->max_capacity();
50   size_t capacity = _space_info->soft_max_capacity();
51   size_t available = _space_info->available();
52 
53   // Make sure the code below treats available without the soft tail.
54   size_t soft_tail = max_capacity - capacity;
55   available = (available > soft_tail) ? (available - soft_tail) : 0;
56 
57   size_t threshold_bytes_allocated = capacity / 100 * ShenandoahAllocationThreshold;
58   size_t min_threshold = capacity / 100 * ShenandoahMinFreeThreshold;
59 
60   if (available < min_threshold) {
61     log_info(gc)("Trigger: Free (" SIZE_FORMAT "%s) is below minimum threshold (" SIZE_FORMAT "%s)",
62                  byte_size_in_proper_unit(available),     proper_unit_for_byte_size(available),
63                  byte_size_in_proper_unit(min_threshold), proper_unit_for_byte_size(min_threshold));
64     return true;
65   }
66 
67   size_t bytes_allocated = _space_info->bytes_allocated_since_gc_start();
68   if (bytes_allocated > threshold_bytes_allocated) {
69     log_info(gc)("Trigger: Allocated since last cycle (" SIZE_FORMAT "%s) is larger than allocation threshold (" SIZE_FORMAT "%s)",
70                  byte_size_in_proper_unit(bytes_allocated),           proper_unit_for_byte_size(bytes_allocated),
71                  byte_size_in_proper_unit(threshold_bytes_allocated), proper_unit_for_byte_size(threshold_bytes_allocated));
72     return true;
73   }
74 
75   return ShenandoahHeuristics::should_start_gc();
76 }
77 
78 void ShenandoahCompactHeuristics::choose_collection_set_from_regiondata(ShenandoahCollectionSet* cset,
79                                                                         RegionData* data, size_t size,
80                                                                         size_t actual_free) {
81   // Do not select too large CSet that would overflow the available free space
82   size_t max_cset = actual_free * 3 / 4;
83 
84   log_info(gc, ergo)("CSet Selection. Actual Free: " SIZE_FORMAT "%s, Max CSet: " SIZE_FORMAT "%s",
85                      byte_size_in_proper_unit(actual_free), proper_unit_for_byte_size(actual_free),
86                      byte_size_in_proper_unit(max_cset),    proper_unit_for_byte_size(max_cset));
87 
88   size_t threshold = ShenandoahHeapRegion::region_size_bytes() * ShenandoahGarbageThreshold / 100;
89 
90   size_t live_cset = 0;
91   for (size_t idx = 0; idx < size; idx++) {
92     ShenandoahHeapRegion* r = data[idx]._region;
93     size_t new_cset = live_cset + r->get_live_data_bytes();
94     if (new_cset < max_cset && r->garbage() > threshold) {
95       live_cset = new_cset;
96       cset->add_region(r);
97     }
98   }
99 }

41   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahAllocationThreshold,  10);
42   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahImmediateThreshold,   100);
43   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahUncommitDelay,        1000);
44   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahGuaranteedGCInterval, 30000);
45   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahGarbageThreshold,     10);
46 }
47 
48 bool ShenandoahCompactHeuristics::should_start_gc() {
49   size_t max_capacity = _space_info->max_capacity();
50   size_t capacity = _space_info->soft_max_capacity();
51   size_t available = _space_info->available();
52 
53   // Make sure the code below treats available without the soft tail.
54   size_t soft_tail = max_capacity - capacity;
55   available = (available > soft_tail) ? (available - soft_tail) : 0;
56 
57   size_t threshold_bytes_allocated = capacity / 100 * ShenandoahAllocationThreshold;
58   size_t min_threshold = capacity / 100 * ShenandoahMinFreeThreshold;
59 
60   if (available < min_threshold) {
61     log_trigger("Free (" SIZE_FORMAT "%s) is below minimum threshold (" SIZE_FORMAT "%s)",
62                 byte_size_in_proper_unit(available),     proper_unit_for_byte_size(available),
63                 byte_size_in_proper_unit(min_threshold), proper_unit_for_byte_size(min_threshold));
64     return true;
65   }
66 
67   size_t bytes_allocated = _space_info->bytes_allocated_since_gc_start();
68   if (bytes_allocated > threshold_bytes_allocated) {
69     log_trigger("Allocated since last cycle (" SIZE_FORMAT "%s) is larger than allocation threshold (" SIZE_FORMAT "%s)",
70                 byte_size_in_proper_unit(bytes_allocated),           proper_unit_for_byte_size(bytes_allocated),
71                 byte_size_in_proper_unit(threshold_bytes_allocated), proper_unit_for_byte_size(threshold_bytes_allocated));
72     return true;
73   }
74 
75   return ShenandoahHeuristics::should_start_gc();
76 }
77 
78 void ShenandoahCompactHeuristics::choose_collection_set_from_regiondata(ShenandoahCollectionSet* cset,
79                                                                         RegionData* data, size_t size,
80                                                                         size_t actual_free) {
81   // Do not select too large CSet that would overflow the available free space
82   size_t max_cset = actual_free * 3 / 4;
83 
84   log_info(gc, ergo)("CSet Selection. Actual Free: " SIZE_FORMAT "%s, Max CSet: " SIZE_FORMAT "%s",
85                      byte_size_in_proper_unit(actual_free), proper_unit_for_byte_size(actual_free),
86                      byte_size_in_proper_unit(max_cset),    proper_unit_for_byte_size(max_cset));
87 
88   size_t threshold = ShenandoahHeapRegion::region_size_bytes() * ShenandoahGarbageThreshold / 100;
89 
90   size_t live_cset = 0;
91   for (size_t idx = 0; idx < size; idx++) {
92     ShenandoahHeapRegion* r = data[idx].get_region();
93     size_t new_cset = live_cset + r->get_live_data_bytes();
94     if (new_cset < max_cset && r->garbage() > threshold) {
95       live_cset = new_cset;
96       cset->add_region(r);
97     }
98   }
99 }
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